Cleavage in Amphibians:

Blastula structure

The late blastula Xenopus embryo has morphologically distinct
regions that are important for understanding gastrulation. These include
the marginal zone (shown in red), the veghetal base (big yolky cells shown
in yellow) and the animal cap (blue). Note that overlying the marginal zone
the superficial cells are colored yellow. That's because in Xenopus
the superficial cells of the marginal zone contribute to the archenteron.